Zhang Yujun, a dairy farmer, and Geng Jinping, a milk salesman, were the only ones of the 21 defendants to be executed. Three received life sentences, one got a suspended death penalty, and the other 15 were jailed for sentences ranging from two to 15 years. The two sentenced to death appealed. China upheld their convictions in March, according to the state news agency Xinhua.

The tainted milk scandal that sickened some 300,000 children came to public attention just after the Beijing Olympics in 2008, prompting accusations that China had covered it up to run a clean international show. The executed Mr. Zhang was convicted of selling 1.3 million pounds of tainted milk powder between July 2007 and August 2008.

The milk producers added melamine to their product, which made it appear to have higher protein content. Melamine, used in fertilizer and plastics, can cause kidney stones. The same chemical has been found in pet food that killed dogs and cats in the US. (Read more on how the tainted milk rippled beyond China here.)

[Chinese and foreign experts said] it pointed to a deeper malaise in Chinese society where private profit often trumps the public good as the country races to create a market economy that has outstripped government regulators.

"China has the problems of any transitional economy," says Yanzhong Huang, a global health expert at Seton Hall University in South Orange, N.J. "But the deeper and more fundamental challenge China faces is a systematic lack of business ethics."